It is known that carbon is one of the most important elements for plants, since it allows them to build support tissues (cellulose is, essentially, a carbon skeleton) and energy reserves (starch, which is a glucose polymer, a sugar) and to have, thanks to photosynthesis, the chemical energy that makes it possible to produce enzymes, proteins and everything else necessary for plant metabolism.
The use of CO2 in aquariums is also chemical: it helps to stabilise the pH at values below 7, difficult to achieve with other methods, which are at the same time compatible with plant growing (such as, for example, filtration over peat) and long-lasting (like additives for lowering pH values).
However, the diffusion of carbon in the water of aquariums is always very limited and in order to have healthy and luxuriant plants it is therefore necessary to administer the carbon they need in an artificial form.
Carbon can be distributed in aquariums by means of various techniques, always in the gaseous state.
The most common method is to dispense amounts of carbon or carbon dioxide directly in the aquarium by using CO2 cylinders equipped with pressure .gauges, pressure reducers and special water diffusers.
According to some systems the CO2 bubbles follow a zigzag path, from the bottom upwards. This path ends in a dome-shaped cap which holds the bubbles until they dissolve in the water, preventing them from being lost in the atmosphere.
The disadvantages of this system consist of the fact that a period of activation is necessary, cleaning is difficult and there is a continuous accumulation of CO2 in the cap, so that at a certain point it is lost. In addition, the area close to the dispenser, and to the cap in particular, is rich in CO2 while the area furthest away is poor in CO2.
In these dispensing models the CO2 cap consists of a plastic rectangle inside which the CO2 is accumulated and from which it inevitably escapes and is scattered on the surface.
This occurs when the mixing time of the gas with the water is greater than the time needed to fill the cap (area close to the cap saturated with carbon dioxide).
According to other distribution systems, the CO2 bubble is forced to enter an atomiser, i.e. a system consisting of a plastic cap to be positioned close to the bottom of the aquarium, where it has to pass through a membrane that divides the bubble into lots of microbubbles which rise directly to the surface and scatter.
This atomiser model does not stand up to high pressures and the device cannot therefore be adjusted to dispense a high number of bubbles per minute.
The Co2 dispenser is sometimes combined with a water delivery pump, but systems ensuring total mixing are not foreseen: the bubbles of gas are not directly struck by the flow of water and/or the microbubbles are not held in the mixing chamber, becoming scattered on the surface, and/or the adjustment of the pump output is dealt with by the user who is unlikely to have the ability to optimise the mixing.
For example, in the patent DE20015086U1, a pump dispenser model, the gas output goes directly to a pump which is designed to reduce the bubble into lots of microbubbles.
In this case the majority of the bubbles struck by the pump flow scatter on the surface, without being completely mixed with the water.
In the known dispensers in which the CO2 bubble is forced to follow a zigzag path, above all those just installed and because of friction along the path, an “activation period” is required because the CO2bubble is unable to complete path and stops after a short distance.
This means that several bubbles accumulate in the same point until the bubble is so big that it slips out of the dispenser and is lost on the surface. After a certain period of time (this is the “activation” period) a coating is created along the entire path which allows the bubble to slide along individually and easily.
There are other distribution systems, but in general their use has revealed considerable disadvantages, which the invention intends to remedy, mainly concerning the fact that the traditional distribution of CO2 is not very effective since some of the dispensed gas bubbles are not completely mixed with the water but rise almost immediately and are lost outside the system, thus thwarting their effect.